302 resultados para Diagramma E-R redattore ER modello relazionale SharpER


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简述了近年来国内外掺Er光纤(EDF)光源的最新发展,详细分析了EDF光源的工作原理;介绍了EDF的基本结构,并概述了其各自的特点;总结了当前几种重要的EDF光源及其研究状况;指出了未来EDF光源发展方向。

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利用Raman散射谱研究了GaN注Er以及Er+O共注样品的振动模,并讨论了共注入O对Er离子发光的影响. 在Raman散射谱中,对于注Er的GaN样品出现了300 cm~(-1)和670 cm~(-1)两个新的Raman峰,而对于Er+O共注样品,除了上述两个峰外,在360 cm~(-1)处出现了另外一个新的峰,其中300 cm~(-1)峰可以用disorder-activated Raman scattering (DARS)来解释,670 cm~(-1)峰是由于与N空位相关的缺陷引起的,而360 cm~(-1)峰是由O注入引起的缺陷络合物产生的. 由于360 cm~(-1)模的缺陷出现,从而导致Er+O共注入GaN薄膜红外光致发光(PL)强度的下降

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利用深能级瞬态谱(DLTS)、傅里叶变换红外光谱(FT-IR)对GaN以及GaN掺Er/Pr的样品进行了电学和光学特性分析.研究发现未掺杂的GaN样品只在导带下0.270eV处有一个深能级;GaN注入Er经900℃,30min退火后的样品出现了四个深能级,能级位置位于导带下0.300eV,0.188eV,0.600eV和0.410eV;GaN注入Pr经1050℃,30min退火后的样品同样出现了四个深能级。能级位置位于导带下0.280eV,0.190eV,0.610eV和0.390eV;对每一个深能级的来源进行了讨论.光谱研究表明,掺Er的GaN样品经900℃,30min退火后,可以观察到Er的1538nm处的发光。而且对能量输运和发光过程进行了讨论.

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对nc-Si/SiO_2<Er>薄膜中纳米硅(nc-Si)、Er~(3+)和非辐射复合缺陷三者间的关系作了研究.在514.5 nm光激发下,nc-Si/SiO_2<Er>薄膜在750nm和1.54μm处存在较强的发光,前者与薄膜中的nc-Si有关,后者对应于Er~(3+)从第一激发态4I13/2到基态4I15/2的辐射跃迁.随薄膜中Er3+含量的提高,1.54μm处的发光强度明显增强,750 nm处的发光强度却降低.H处理可以明显增强薄膜的发光强度,但是对不同退火温度样品,处理效果却有所不同.根据以上实验结果,可得如下结论:在nc-Si颗粒附近的Er~(3+)和其他的缺陷组成了nc-Si颗粒内产生的束缚激子的非辐射复合中心,束缚激子通过Er~(3+)的非辐射复合,激发Er~(3+)产生1.54μm处的发光,同时降低了750nm处的发光强度.nc-Si颗粒附近其他非辐射复合中心的存在会降低Er~(3+)被激发的概率,引起1.54μm处的发光强度降低.

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采用表面钝化和MOCVD低温生长在蓝宝石(0001)面(即C面)和蓝宝石(1(1-bar)02)面(即R面)上形成了InGaN量子点,并构成了该量子点的多层结构。原子力显微镜测试的结果表明单层InGaN量子点平均宽约40nm,高约15nm;而多层量子点上层的量子点则比单层的InGaN量子点大。R面蓝宝石衬底上生长的InGaN量子点和C面蓝宝石衬底上生长的InGaN量子点相比,其PL谱不仅强度高,而且没有多峰结构。这是由于在C面蓝宝石衬底上生长的InGaN/GaN多层量子点沿生长方向[0001]存在较强的内建电场,而在R面蓝宝石衬底上得到的多层量子点沿着生长方向[11(2-bar)0]没有内建电场。InGaN量子点变温光致发光(PL)谱研究发现量子点相关的峰有快速红移现象,这是量子点系统所特有的PL谱特征。用在R面蓝宝石上生长的InGaN量子点作有源层有望避免内建电场的影响,得到高量子效率且发光波长稳定的发光器件。

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采用光致发光(PL)谱和傅里叶变换红外(FTIR)谱研究了掺铒a-SiO_x:H(a-SiO_x:H<Er>)薄膜在不同退火温度下光学性质和微观结构的变化。PL谱的测量结果表明:薄膜在1.54μm的Er~(3+)发光和750nm处的可风发光随退火温度有相同的变化趋势,这种变化和薄膜在退火过程中微观结构的变化有着密切关系。FTIR谱的分析表明:a-SiO_x:H薄膜是一种两相结构,富硅相镶嵌在富氧相中。两者的成分可近似用a-SiO_(x≈0.3):H和a-SiO_(x≈1.5):H表示,前者性质接近于氢化非晶硅(a-Si:H),后者性质接近于a-SiO_2。富硅相在退火中的变化对Er~(3+)的发光强度有重要影响。

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本文采用集团模型和推广的Hucket分子轨道理论(EHMO)计算c-Si中Er点缺陷及Er-O复合缺陷的原子构型及电子结构。计算结果符合实验及一些文献的第一性原理计算结果,解释了Er有c-Si中的发光特性。

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材料科学开放实验室基金,光学信息技术科学教育部开放实验室基金

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用溶胶-凝胶方法合成了掺铒(掺杂浓度10~20/cm~3)的二氧化硅玻璃。在室温下可产生1.45μm波长的红外荧光。实验结果表明

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用光致发光谱(PL)、傅里叶变换红外吸收谱(FTIR)和X射线衍射谱(XRD)等研究了稀土(Er)和氧(O)双离子注入GaAs和Si的发光特性和高效发光机理。测量并分析了该材料的FTIR和XRD谱;对该材料的高效发光机制作了较深入地探讨和澄清。

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于2010-11-23批量导入

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分别在InP、GaAs和Si中以7×10<′14>和1×10<′15>cm<′-2>的剂量进行Er离子注入, 并采用闭管、快速和炉退火等热处理。低温光致发光(PL)、反射式高等电子衍射和卢瑟福背散射实验研究表明, 上述样品中Er<′3+>离子特征发光的中心波长均出现在1.5μm处, 其中InP的发光峰最强, 而注入损伤的恢复是影响Er<′3+>发光的重要因素之一。卢瑟福背散射分析进一步证实退火后Er原子在Si中向表面迁移, 而在InP中的外扩散较小, 并比较了Er在InP和Si晶格中的占位情况。图7参12

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于2010-11-23批量导入

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Erbium-doped silica glasses were made by sol-gel process. Intensive photoluminescence (PL) spectra from the Er-doped silica glasses at room temperature were measured. A broadband peak at 1535 ma, corresponding to the I-4(13/2)-I-4(15/2) transition, its full width at half-maximum (FWHM) of 10 nm, and a shoulder at 1546 nm in the PL spectra were observed. At lower temperatures, main line of 1535 nm and another line of 1552 Mn instead of 1546 nm appear. So two types of luminescence centers must exist in the samples at different temperature. The intensity of main line does not decrease obviously with increasing temperature. By varying the Er ion concentration in the range of 0.2 wt% - 5wt%, the highest photoluminescence intensity was obtained at 0.2wt% erbium doped concentration. Luminescence intensity decreases with increasing erbium concentration. Cooperative upconversion was used to explain the concentration quenching of luminescence from silica glass with high erbium concentration. Extended X-ray absorption fine structure measurements were carried out. It was found that the majority of the erbium impurities in the glasses have a local structure of eight first neighbor oxygen atoms at a mean distance of 0.255 nm, which is consistent with the typical coordination structure of rare earth ion.

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Exciton-mediated energy transfer model in Er-doped silicon was presented. The emission intensity is related to optically active Er concentration, lifetime of excited Er3+ ion and spontaneous emission. The thermal quenching of the Er luminescence in Si is caused by thermal ionization of Er-bound exciton complex and nonradiative energy back-transfer processes, which correspond to the activation energy of 6.6 and 47.4 meV, respectively. Er doping in silicon introduces donor states, a large enhancement in the electrical activation of Er (up to two orders of magnitude) is obtained by co-implanting Er with O. It appears that the donor states are the gateway to the optically active Er. (C) 2000 Elsevier Science B.V. All rights reserved.